Imaging apparatus having a shake correction function in both of an interchangeable lens and a camera body

ABSTRACT

The interchangeable lens includes: a shake correction processing unit configured to calculate an amount of shake correction for the correction lens and an imaging device; and a lens driving unit configured to perform image blur correction by moving the correction lens in a plane perpendicular to an optical axis based on an output from the shake correction processing unit. The camera body includes a device driving unit configured to perform image blur correction by moving the imaging device in a plane perpendicular to the optical axis. The lens driving unit moves the correction lens to a predetermined center position and the device driving unit shifts the imaging device by an amount corresponding to an amount of the movement of the correction lens to the center position at a beginning of exposure. The lens driving unit drives the correction lens during a period of the exposure.

BACKGROUND

Technical Field

The present disclosure relates to an imaging apparatus that has a shakecorrection function in both of an interchangeable lens and a camerabody.

Description of the Related Art

There have been imaging apparatuses that are provided with a detectionunit (a gyro sensor or the like) which detects a shake of the imagingapparatus. Interchangeable-lens cameras as the imaging apparatuses havethe detection unit such as a gyro sensor which detects a shake of theimaging apparatus provided at least in one of the interchangeable lensand the camera body as described in, for example, Patent Literature 1.In the camera which has the detection unit provided in theinterchangeable lens, the camera shifts a position of a shake correctionlens provided in the interchangeable lens based on the detection resultfrom the detection unit. On the other hand, in the camera which has thedetection unit provided in the camera body, the camera shifts a positionof an imaging device (an image sensor) provided in the camera body basedon the detection result from the detection unit.

Those types of the imaging apparatus reduce influences of the camerashake on a captured image by detecting vibrations in a frequency bandaround 1 Hz to 10 Hz transmitted from user's hands and by driving lensesin the interchangeable lens or an imaging sensor in the camera body orboth of the lenses and the imaging sensor based on the detection result.

CITATION LIST Patent Literature

PTL 1: Unexamined Japanese Patent Publication No. 2009-251492

SUMMARY

In a case where an imaging apparatus reduces an influence of a shake ofthe imaging apparatus on a captured image by shifting a correction lensor the imaging apparatus according to the shake, an amount of shift ofthe correction lens or the like is limited by such factors as a lensbarrel size. Therefore, when the imaging apparatus suffers a largeamount of shake, the imaging apparatus cannot drive the correction lensor the like by an enough amount to cancel the shake and, as a result,cannot sufficiently realize a shake correction function.

The present disclosure provides an imaging apparatus that is able toeffectively use a shake correction range.

A first aspect of the present disclosure provides an imaging apparatusprovided with an interchangeable lens and a camera body. Theinterchangeable lens includes: a correction lens configured to correctan image blur; a shake detection unit configured to detect a shake of atleast one of the camera body and the interchangeable lens; a shakecorrection processing unit configured to calculate an amount of shakecorrection for the correction lens and an imaging device based on anoutput from the shake detection unit; and a lens driving unit configuredto perform image blur correction by moving the correction lens in aplane perpendicular to an optical axis based on an output from the shakecorrection processing unit. The camera body includes: an imaging deviceconfigured to generate image data by imaging an object image which isformed by the interchangeable lens; and a device driving unit configuredto perform image blur correction by moving the imaging device in a planeperpendicular to the optical axis. The lens driving unit moves thecorrection lens to a predetermined center position and the devicedriving unit shifts the imaging device by an amount corresponding to anamount of the movement of the correction lens to the center position ata beginning of exposure of the imaging device. The lens driving unitdrives the correction lens around the center position based on an outputfrom the shake correction processing unit during a period of theexposure.

A second aspect of the present disclosure provides an interchangeablelens to be mounted to a camera body. The interchangeable lens includes:a correction lens configured to correct an image blur; a shake detectionunit configured to detect a shake of at least one of the camera body andthe interchangeable lens; a shake correction processing unit configuredto calculate an amount of shake correction for the correction lens andan imaging device based on an output from the shake detection unit; alens driving unit configured to perform image blur correction by movingthe correction lens in a plane perpendicular to an optical axis based onan output from the shake correction processing unit; and a communicationunit configured to communicate with the camera body. The lens drivingunit moves the correction lens to a predetermined center position at abeginning of exposure of the imaging device, and drives the correctionlens around the center position based on the output from the shakecorrection processing unit during a period of the exposure. Thecommunication unit transmits to the camera body information indicatingan amount of the movement of the correction lens to the center positionat the beginning of the exposure.

A third aspect of the present disclosure provides a camera body to whichan interchangeable lens is to be mounted. The camera body includes: animaging device configured to generate image data by imaging an objectimage which is formed by the interchangeable lens; a device driving unitconfigured to perform image blur correction by moving the imaging devicein a plane perpendicular to the optical axis; and a communication unitconfigured to receive from the interchangeable lens informationindicating an amount of the movement of the correction lens to thecenter position. The device driving unit is configured to shift theimaging device during a period of exposure of the imaging device by anamount corresponding to the amount of the movement indicated by thereceived information.

The present disclosure can provide an imaging apparatus that is able toeffectively use a shake correction range.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a digitalcamera according to a first exemplary embodiment;

FIG. 2 is a block diagram illustrating a configuration of an OIS(Optical Image Stabilizer) processing unit of the digital cameraaccording to the first exemplary embodiment;

FIG. 3 is a block diagram illustrating a configuration of a BIS (BodyImage Stabilizer) processing unit of the digital camera according to thefirst exemplary embodiment;

FIG. 4 is a frequency characteristics graph of phase delay versusseveral different communication frequencies;

FIG. 5 is a frequency characteristics graph of correction performancedeterioration versus several different communication frequencies;

FIG. 6 is a graph showing time variations for a shake detection signal,a low-frequency shake correction signal (BIS control signal), and ahigh-frequency shake correction signal (OIS control signal) in a shakecorrection process according to the first exemplary embodiment;

FIG. 7 is a block diagram illustrating a configuration of an OISprocessing unit of a digital camera according to a second exemplaryembodiment;

FIG. 8 is a block diagram illustrating a configuration of a BISprocessing unit of the digital camera according to the second exemplaryembodiment;

FIG. 9 is a flow chart showing steps of a shake correction process inthe digital camera according to the second exemplary embodiment;

FIG. 10 is a graph showing changes in a shake detection signal, a BIScontrol signal, and an OIS control signal in a shake correction processaccording to the second exemplary embodiment;

FIG. 11 is a block diagram illustrating another configuration of the OISprocessing unit of the digital camera according to the second exemplaryembodiment; and

FIG. 12 is a block diagram illustrating another configuration of the BISprocessing unit of the digital camera according to the second exemplaryembodiment.

DETAILED DESCRIPTION

Exemplary embodiments of the present disclosure will be described belowwith reference to the drawings as required. However, an unnecessary partof the detailed description about the prior art and substantially thesame configuration may be omitted. That is for simplicity of thedescription. The inventors provide the following description and theaccompanying drawings for those skilled in the art to fully understandthe present disclosure and do not intend to limit the subject matter ofthe claims to the description and the drawings. The imaging apparatuswill be exemplified by a digital camera below.

First Exemplary Embodiment

The digital camera according to the first exemplary embodiment has ashake correction function that reduces influences of a shake of thedigital camera on a captured image in both of an interchangeable lensand a camera body. Specifically, in the interchangeable lens, the shakecorrection function reduces the influences of the shake by causing ashake detection unit such as a gyro sensor to detect a shake, causing ashake correction processing unit to calculate a shake correction signal,and moving a shake correction lens in a plane perpendicular to anoptical axis of an optical system according to a shake in a highfrequency domain of the shake correction signal. On the other hand, inthe camera body, the shake correction function reduces the influences ofthe shake by moving an image sensor such as a CCD in a planeperpendicular to the optical axis of the optical system according to ashake in a low frequency domain of the shake correction signalcalculated by the shake correction processing unit. A configuration andoperations of the digital camera according to the present exemplaryembodiment will be described in detail below.

In the description below, a function of correcting a shake by shiftingthe shake correction lens in the interchangeable lens will be referredto as an “OIS (Optical Image Stabilizer) function”. Further, a functionof correcting a shake by shifting an imaging device in the camera bodywill be referred to as a “BIS (Body Image Stabilizer) function”. It isassumed that digital camera 1 according to the first exemplaryembodiment has the OIS function able to correct a shake with higheraccuracy as compared to the BIS function. In this context, whether thefunction is able to correct a shake with high accuracy or not isdetermined on the basis of whether the function is subject to a smallfollow-up residual difference for the shake correction signal or not,for example, whether the function has good follow-up capability andresponsibility to a high-frequency component or not.

1. Configuration

FIG. 1 is a block diagram illustrating a configuration of the digitalcamera according to the first exemplary embodiment. Digital camera 1includes camera body 100 and interchangeable lens 200 detachably fixedto camera body 100.

1-1. Camera Body

Camera body 100 has CCD 110, liquid crystal monitor 120, cameracontroller 140, body mount 150, power source 160, and card slot 170.

Camera controller 140 controls an overall operation of digital camera 1by controlling the respective structural elements constituting camerabody 100 and interchangeable lens 200 in addition to CCD 110 in responseto a user operation on release button 130 which functions as a receptionunit configured to receive a photographing instruction from a user.Camera controller 140 transmits a vertical synchronizing signal totiming generator 112. In parallel to that process, camera controller 140generates an exposure synchronizing signal. Camera controller 140periodically transmits the generated exposure synchronizing signal tolens controller 240 via body mount 150 and lens mount 250. Cameracontroller 140 uses DRAM 313 as a work memory in performing a controloperation or an image processing operation.

CCD 110 generates image data by imaging an object image which isincident through interchangeable lens 200. The generated image data isdigitized in AD converter 111. The digitized image data is subjected topredetermined image processing by camera controller 140. Thepredetermined image processing includes a gamma correction process, awhite balance correction process, a blemish correction process, a YCconversion process, an electronic zoom process, and a JPEG compressionprocess, for example.

CCD 110 operates with timing controlled by timing generator 112. Theoperations of CCD 110 includes but not limited to an imaging operationof a still image and an imaging operation of a through image. Thethrough image, which is primarily a moving image, is displayed on liquidcrystal monitor 120 for the user to compose the still image to beimaged.

Liquid crystal monitor 120 displays an image represented by displayimage data which has undergone the image processing in camera controller140. Liquid crystal monitor 120 can selectively display the moving imageand the still image.

Card slot 170 into which memory card 171 can be inserted controls memorycard 171 based on control from camera controller 140. Digital camera 1is able to store image data into memory card 171 or is able to read theimage data out from memory card 171.

Power source 160 supplies power to the respective elements in digitalcamera 1.

Body mount 150 (an example of a second communication unit) canmechanically and electrically connect with lens mount 250 (an example ofa first communication unit) of interchangeable lens 200. Camera body 100and interchangeable lens 200 can transmit and receive data to and fromeach other via a connector installed in body mount 150 and in lens mount250. Body mount 150 transmits the exposure synchronizing signal receivedfrom camera controller 140 to lens controller 240 via lens mount 250.Further, body mount 150 transmits the other control signals receivedfrom camera controller 140 to lens controller 240 via lens mount 250.Still further, body mount 150 transmits the signal received from lenscontroller 240 via lens mount 250 to camera controller 140. Stillfurther, body mount 150 supplies power from power source 160 to thewhole of interchangeable lens 200 via lens mount 250.

Also, camera body 100 further implements a configuration of realizingthe BIS function of correcting a camera shake by having gyro sensor 184(a shake detection unit) which detects a shake of camera body 100 andBIS processing unit 183 which generates the shake correction signal andcontrols a shake correction process based on a detection result fromgyro sensor 184. Further, camera body 100 has CCD driving unit 181 whichmoves CCD 110, and position sensor 182 which detects a position of CCD110. CCD driving unit 181 can be made with a magnet and a planar coil,for example. Position sensor 182 is a sensor which detects a position ofCCD 110 in a plane perpendicular to an optical axis of an opticalsystem. Position sensor 182 can be made with a magnet and a Hallelement, for example. Based on a signal from gyro sensor 184 and asignal from position sensor 182, BIS processing unit 183 controls CCDdriving unit 181 to shift CCD 110 in a plane perpendicular to theoptical axis so that the shift offsets the shake of camera body 100.Although an imaging sensor provided in camera body 100 includes a CCD inthe first exemplary embodiment, the imaging sensor may include adifferent imaging sensor such as a CMOS sensor. Also, CCD driving unit181 may be configured with a different actuator such as a stepping motoror an ultrasonic motor. Incidentally, in a case where a stepping motoris used as the actuator, camera body 100 can implement open-loop controland, accordingly, can even dispose of position sensor 182.

1-2. Interchangeable Lens

Interchangeable lens 200 has the optical system, lens controller 240,and lens mount 250. The optical system includes zoom lens 210, OIS(Optical Image Stabilizer) lens 220 for correcting a camera shake, andfocus lens 230.

Zoom lens 210 is for changing a magnification of an object image whichis formed by the optical system. Zoom lens 210 includes one or morelenses. Zoom lens driving unit 211, which includes a user-operable partsuch as a zoom ring, transmits a user operation to zoom lens 210 tocause zoom lens 210 to move along an optical axis direction of theoptical system.

Focus lens 230 is for changing a focus state of an object image which isformed on CCD 110 by the optical system. Focus lens 230 includes one ormore lenses.

Focus lens driving unit 233, which includes a motor, moves focus lens230 along the optical axis of the optical system based on the control oflens controller 240. Focus lens driving unit 233 can be made with, forexample, a DC motor, a stepping motor, a servo motor, or an ultrasonicmotor.

OIS lens 220 is a lens for correcting a blur in the object image formedby the optical system of interchangeable lens 200 in the OIS function ofcorrecting a camera shake. OIS lens 220 decreases a blur in the objectimage on CCD 110 by moving in a direction that offsets a shake ofdigital camera 1. OIS lens 220 includes one or more lenses. OISprocessing unit 223 controls OIS driving unit 221 based on an outputfrom position sensor 222 and an output from gyro sensor 224 (a shakedetector). In response to the control from OIS processing unit 223, OISdriving unit 221 shifts OIS lens 220 in a plane perpendicular to theoptical axis of the optical system.

OIS driving unit 221 can be made with, for example, a magnet and aplanar coil. Position sensor 222 is a sensor which detects a position ofOIS lens 220 in the plane perpendicular to the optical axis of theoptical system. Position sensor 222 can be made with a magnet and a Hallelement, for example. In the first exemplary embodiment, OIS drivingunit 221 may include a different actuator such as an ultrasonic motor.

Gyro sensor 184 or gyro sensor 224 detects a shake in the yaw directionand a shake in the pitch direction based on an angular change per unittime, i.e., an angular velocity of digital camera 1. Gyro sensor 184 orgyro sensor 224 outputs an angular velocity signal which indicates anamount of the detected shake (the detected angular velocity) to OISprocessing unit 223 or BIS processing unit 183. The angular velocitysignal output from gyro sensor 184 or gyro sensor 224 may contain awide-band frequency component resulting from a camera shake, amechanical noise, or the like. Although a gyro sensor is used as anangular velocity detection unit in the first exemplary embodiment, theother sensors can be used as far as the sensor is able to detect a shakeof digital camera 1.

Camera controller 140 and lens controller 240 may include a hardwiredelectronic circuit or a microcomputer using a program. That is also thecase with OIS processing unit 223 or BIS processing unit 183. Forexample, camera controller 140 and lens controller 240 as well as OISprocessing unit 223 or BIS processing unit 183 may include semiconductorcircuits such as a CPU, an MPU, a GPU, an ASIC, an FPGA, and the like.

1-3. OIS Processing Unit

A configuration of OIS processing unit 233 in interchangeable lens 200will be described with reference to FIG. 2. OIS processing unit 233includes ADC (analogue-to-digital converter)/LPF (low-pass filter) 305,HPF (high-pass filter) 306, phase compensation unit 307, integrator 308,LPF 309, adder 310, and PID (proportional-integral-derivative) controlunit 311.

ADC/LPF 305 converts the angular velocity signal output from gyro sensor224 from an analog form into a digital form. Further, ADC/LPF 305 cutsoff a high-frequency component from the converted digital form of theangular velocity signal in order to remove a noise and extract only ashake of digital camera 1. A frequency of a shake transmitted from theuser's hands is as low as 1 Hz to 10 Hz; therefore, in consideration ofthe fact, a cutoff frequency of the LPF is set. In a case where digitalcamera 1 has only a negligible noise, digital camera 1 can omit the LPFfunction.

HPF 306 cuts off a predetermined low-frequency component contained in asignal received from ADC/LPF 305 to cut off a drift component. Phasecompensation unit 307 corrects a phase delay which results from causesincluding undermentioned OIS driving unit 221 and lens-to-camera bodycommunication, described later, in a signal received from HPF 306.

Integrator 308 integrates a signal indicating an angular velocity of theshake (vibration), input from phase compensation unit 307 and generatesa signal indicating an angle of the shake (vibration). Hereinafter, thesignal generated by integrator 308 will be referred to as “shakecorrection signal.”

The shake correction signal from integrator 308 is input to LPF 309 andadder 310. LPF 309 cuts off a high-frequency component of the shakecorrection signal and lets a low-frequency component, which will bereferred to as “low-frequency shake correction signal” hereinafter,passed through. The low-frequency shake correction signal is a signalindicating an amount of shake correction corresponding to a shake in alow frequency domain. Meanwhile, the cutoff frequency of LPF 309 is setto, for example, 5 Hz in consideration of the frequency of the shaketransmitted from the user's hands around 1 Hz to 10 Hz. Although the LPFis used for the generation of the low-frequency shake correction signalin the first exemplary embodiment, the LPF of any order such as afirst-order LPF, a second-order LPF, or the LPF of higher order may beused without limitation. Further, any other filter may be used as far asthe filter cuts a high-frequency component such as LSF (low shelffilter). Still further, the cutoff frequency is not limited to 5 Hz andmay be changed depending on a transmitted shake, the imaging apparatusused, and imaging conditions. Still further, the filter configuration isnot limited to the above described configuration and may be a differentconfiguration such as a configuration in which the order of HPF 306 andintegrator 308, for example, is reversed.

Adder 310 extracts the high-frequency component of the shake correctionsignal, which will be referred to as “high-frequency shake correctionsignal” hereinafter, by subtracting the low-frequency component of theshake correction signal, which has been extracted by LPF 309, from theshake correction signal input from integrator 308. The high-frequencyshake correction signal is a signal indicating an amount of shakecorrection corresponding to a shake in a high frequency domain. Thehigh-frequency shake correction signal is input to PID control unit 311.On the other hand, the low-frequency shake correction signal istransmitted to camera body 100.

PID control unit 311 performs PID control based on a difference betweenthe input high-frequency shake correction signal and current positionalinformation of OIS lens 220 received from position sensor 222 togenerate a driving signal for OIS driving unit 221 and transmits thedriving signal to OIS driving unit 221. OIS driving unit 221 drives OISlens 220 based on the driving signal.

1-4. BIS Processing Unit

A configuration of BIS processing unit 183 in camera body 100 will bedescribed with reference to FIG. 3. BIS processing unit 183 includes ADC(analogue-to-digital converter)/LPF (low-pass filter) 405, HPF(high-pass filter) 406, phase compensation unit 407, integrator 408,selector 412, and PID (proportional-integral-derivative) control unit410.

Basic functions of ADC/LPF 405, HPF 406, phase compensation unit 407,integrator 408, and PID control unit 410 are the same as the functionsof corresponding elements in OIS processing unit 223.

BIS processing unit 183 is configured to perform the shake correctionprocess particularly based on one of the output from gyro sensor 184provided in camera body 100 (an output from integrator 408) and thelow-frequency shake correction signal received from interchangeable lens200. Therefore, BIS processing unit 183 has selector 412 which isconfigured to select one of the output from gyro sensor 184 provided incamera body 100 (an output from integrator 408) and the low-frequencyshake correction signal received from interchangeable lens 200 andoutput the selected one to PID control unit 410. In a case where camerabody 100 implements a shake correction function by itself to meet suchcircumstances of an interchangeable lens that does not have a shakecorrection function, selector 412 selects the output from gyro sensor184 provided in camera body 100 (an output from integrator 408) for theoutput to PID control unit 410. Selector 412 is controlled by cameracontroller 140.

PID control unit 410 generates a driving signal for shifting CCD 110based on an output from position sensor 182 and the output fromintegrator 408 or the output from the low-frequency shake correctionsignal from interchangeable lens 200 and outputs the driving signal toCCD driving unit 181. CCD driving unit 181 shifts the position of CCD110 based on the driving signal.

2. Shake Correction Process

The shake correction process in digital camera 1 of the above describedconfiguration will be described. In the description below, the shakecorrection process will be described by taking an example of a casewhere digital camera 1 drives OIS lens 220 and CCD 110 based on thesignal from gyro sensor 224 provided in interchangeable lens 200 amongthe two gyro sensors 224 and 184. That is, digital camera 1 uses gyrosensor 224 provided in interchangeable lens 200. On that occasion,selector 412 in BIS processing unit 183 is controlled to select thelow-frequency shake correction signal and output the low-frequency shakecorrection signal to PID control unit 410. Further on that occasion,digital camera 1 operates by using interchangeable lens 200 which hasgyro sensor 224 to be used as a master and by using camera body 100 as aslave.

OIS processing unit 223 receives a detection signal from gyro sensor 224and generates the shake correction signal from the received detectionsignal. Then, OIS processing unit 223 separates the high-frequency shakecorrection signal and the low-frequency shake correction signal from theshake correction signal. OIS processing unit 223 generates the drivingsignal for shifting OIS lens 220 based on the high-frequency shakecorrection signal and the positional information from position sensor222 and transmits the driving signal to OIS driving unit 221. Accordingto the driving signal from OIS processing unit 223, OIS driving unit 221causes OIS lens 220 to shift in the plane perpendicular to the opticalaxis to cancel the high-frequency shake among the shake detected by gyrosensor 224.

The low-frequency shake correction signal generated in OIS processingunit 223 is transmitted to camera body 100 by lens-to-camera bodycommunication over lens mount 250 and body mount 150. On that occasion,in BIS processing unit 183 of camera body 100, selector 412 iscontrolled to select the low-frequency shake correction signal frominterchangeable lens 200. BIS processing unit 183 generates the drivingsignal for shifting CCD 110 based on the low-frequency shake correctionsignal from interchangeable lens 200 and the positional information fromposition sensor 182 and outputs the driving signal to CCD driving unit181. According to the driving signal from BIS processing unit 183, CCDdriving unit 181 causes CCD 110 to shift in the plane perpendicular tothe optical axis to cancel the low-frequency shake detected by gyrosensor 224. Incidentally, although digital camera 1 performs thelens-to-camera body communication over lens mount 250 and body mount 150in the first exemplary embodiment, it may perform the communication byusing optical communications or radio communications.

As described above, digital camera 1 according to the first exemplaryembodiment activates the shake correction function provided atinterchangeable lens 200 based on the high-frequency component in thedetected shake correction signal and activates the shake correctionfunction provided at camera body 100 based on the low-frequencycomponent in the detected shake correction signal. Thus, in the firstexemplary embodiment, digital camera 1 shares the shake correctionfunction between camera body 100 and interchangeable lens 200 so that itonly needs to exclusively correct a high-frequency shake atinterchangeable lens 200. As a result, digital camera 1 is able toeffectively use a correction range of OIS lens 220 at interchangeablelens 200.

Since the low-frequency shake correction signal is transmitted frominterchangeable lens 200 to camera body 100 in the first exemplaryembodiment, the phase of the low-frequency shake correction signalreceived at camera body 100 is delayed due to the influence of a cycleof the lens-to-camera body communication. OIS processing unit 223 isable to prevent correction performance deterioration also by advancingthe phase of the high-frequency shake correction signal in considerationof the phase delay of the low-frequency shake correction signal. In thiscase, digital camera 1 calculates an amount of phase of thehigh-frequency shake correction signal to be advanced based on the cycleof the lens-to-camera body communication. Digital camera 1 according tothe first exemplary embodiment uses the low-frequency shake correctionsignal for the shake correction signal to be transmitted from themaster. With that configuration, digital camera 1 is able to reduce theinfluence of the phase delay of the signal due to the lens-to-camerabody communication.

FIG. 4 is a frequency characteristics graph of phase delay calculatedfor several different communication frequencies between interchangeablelens 200 and camera body 100. In FIG. 4, a horizontal axis represents afrequency of the shake correction signal (shake frequency) transmittedbetween interchangeable lens 200 and camera body 100 and a vertical axisrepresents the phase delay. It is apparent from FIG. 4 that the lowerthe communication frequency is, the longer the phase delay becomes forthe same shake frequency. FIG. 5 is a frequency characteristics graph ofcorrection performance deterioration calculated for several differentcommunication frequencies. In FIG. 5, the horizontal axis represents theshake frequency and the vertical axis represents a proportion(percentage) of the shake which is caused by the phase delay and cannotbe corrected by digital camera 1. It is apparent from FIG. 4 that thelower the communication frequency, the more the shake which is leftuncorrected due to the phase delay, thus, the more the shake yet to becorrected. Further, the higher the shake frequency is, the moresignificant the correction performance deterioration is.

In consideration of those facts, the communication frequency betweeninterchangeable lens 200 and camera body 100 for the transmission of thelow-frequency shake correction signal is set to 250 Hz or higher in thefirst exemplary embodiment.

FIG. 6 is a graph showing respective variations for an original shakecorrection signal which is the shake correction signal (correctionsignal before separated into the high-frequency component and thelow-frequency component), the low-frequency shake correction signal, andthe high-frequency shake correction signal in the shake correctionprocess according to the first exemplary embodiment. Digital camera 1calculates the low-frequency shake correction signal by passing theoriginal shake correction signal through the LPF. Digital camera 1calculates the high-frequency shake correction signal by subtracting thelow-frequency shake correction signal from the original shake correctionsignal. As shown in FIG. 6, the phase of the low-frequency shakecorrection signal which is denoted by a bold dashed line is delayed fromthe phase of the original shake correction signal which is denoted by athin dashed line. Digital camera 1 advances the high-frequency shakecorrection signal which is denoted by a thin dashed line by subtractingthe low-frequency shake correction signal which has the delayed phasefrom the original shake correction signal.

Although interchangeable lens 200 is used as the master in the firstexemplary embodiment, camera body 100 may be used as the master. Thatis, digital camera 1 may control the OIS function and the BIS functionbased on the output from gyro sensor 184 of camera body 100. For thiscase, BIS processing unit 183 is preferably configured to separate thelow-frequency shake correction signal and the high-frequency shakecorrection signal from the shake correction signal calculated on thebasis of the detection signal from gyro sensor 184 as illustrated inFIG. 3. The low-frequency shake correction signal is transmitted fromcamera body 100 to interchangeable lens 200, in which driving of OISlens 220 is controlled based on the low-frequency shake correctionsignal. On the other hand, in camera body 100, driving of CCD 110 iscontrolled based on the high-frequency shake correction signal. In thiscase, digital camera 1 is able to effectively use a correction range ofBIS at camera body 100.

That is, digital camera 1 only needs to control the shake correctionfunction of one of interchangeable lens 200 and camera body 100 that isused as the master based on the high-frequency shake correction signaland to control the shake correction function of the other ofinterchangeable lens 200 and camera body 100 based on the low-frequencyshake correction signal.

In this case, the selection of the master from camera body 100 andinterchangeable lens 200 is preferably based on accuracy of the shakecorrection by the OIS function and by the BIS function. Since digitalcamera 1 according to the first exemplary embodiment has the OISfunction able to perform the shake correction with higher accuracy thanthe BIS function is, digital camera 1 selects interchangeable lens 200for the master. With that configuration, digital camera 1 is able toefficiently use the two shake correction functions. As shown in FIG. 6,the high-frequency component of the shake correction signal representsvibrations of shorter cycles as compared to the low-frequency component.Therefore, the high-frequency component of the shake correction signalrequires the shake correction of higher accuracy as compared to thelow-frequency component. Then, digital camera 1 according to the firstexemplary embodiment corrects the high-frequency component of the shakecorrection signal by using the OIS function which is able to correct theshake with high accuracy but corrects the low-frequency component of theshake correction signal by using the BIS function which corrects theshake with accuracy not as high as that of the OIS function. For thatpurpose, digital camera 1 is configured to cause the master to activelytransmit the low-frequency component of the shake correction signal tothe slave.

Digital camera 1 may perform the shake correction based on thehigh-frequency shake correction signal and the low-frequency shakecorrection signal continuously or exclusively during an exposure. Forexample, OIS processing unit 223 performs the shake correction processbased on the signal from gyro sensor 224 provided in interchangeablelens 200 before pushing of release button 130 which is configured toreceive a photographing instruction from the user. Meanwhile, BISprocessing unit 183 executes a stop operation at a center position.Then, in response to the pushing of release button 130, CCD driving unit181 starts the shake correction process based on the low-frequency shakecorrection signal received from interchangeable lens 200 and continuesperforming the shake correction process until the end of the exposure.After the exposure is finished, BIS processing unit 183 executes thestop operation at a center position again. Meanwhile, during apredetermined period after the release button 130 receives thephotographing instruction from the user (a period as long as or longerthan an exposure period), the low-frequency shake correction signal istransmitted from interchangeable lens 200 to camera body 100 via lensmount 250 and body mount 150. With that configuration, digital camera 1corrects the shake in response only to the high-frequency shakecorrection signal by the OIS function before the pushing of releasebutton 130. Further, digital camera 1 corrects the shake both inresponse to the high-frequency shake correction signal by the OISfunction and in response to the low-frequency shake correction signal bythe BIS function after the pushing of release button 130. Accordingly,before the exposure, digital camera 1 is able to perform the image blurcorrection with restrained power consumption, and during the exposure,digital camera 1 is able to perform the image blur correction witheffective image blur correction.

3. Summarization

Digital camera 1 according to the first exemplary embodiment hasinterchangeable lens 200 and camera body 100 with one of interchangeablelens 200 and camera body 100 acting as the master and the other actingas the slave. Interchangeable lens 200 includes OIS lens 220 configuredto correct an image blur and OIS driving unit 221 configured to performimage blur correction by moving OIS lens 220 in a plane perpendicular tothe optical axis. Camera body 100 includes CCD 110 configured togenerate image data by imaging an object image which is formed byinterchangeable lens 200 and CCD driving unit 181 configured to performimage blur correction by moving CCD 110 in a plane perpendicular to theoptical axis. Digital camera 1 according to the first exemplaryembodiment has, at one of interchangeable lens 200 and camera body 100,which acts as the master, gyro sensor 224 or gyro sensor 184 configuredto detect a shake of camera body 100 or interchangeable lens 200 or bothof camera body 100 and interchangeable lens 200 and shake correctionprocessing unit (OIS processing unit 223, BIS processing unit 183)configured to calculate an amount of shake correction for OIS lens 220and CCD 110 from an output from gyro sensor 224 or gyro sensor 184.

The shake correction processing unit (OIS processing unit 223, BISprocessing unit 183) calculates an amount of image blur correction forthe image blur occurred in digital camera 1 and separates the shakecorrection signal which indicates an amount of shake occurred in digitalcamera 1 into the shake correction signal (the low-frequency shakecorrection signal) corresponding to a shake in the low frequency domain,and the shake correction signal (the high-frequency shake correctionsignal) corresponding to a shake in the high frequency domain. One ofOIS driving unit 221 and CCD driving unit 181 functions as a drivingunit in the master and performs the image blur correction based on theshake correction signal of the high frequency domain. The other of OISdriving unit 221 and CCD driving unit 181 performs the image blurcorrection based on the shake correction signal of the low frequencydomain.

With that configuration, digital camera 1 can share the shake correctionfunction between camera body 100 and interchangeable lens 200 so that itonly needs to exclusively correct the high-frequency shake atinterchangeable lens 200. As a result, digital camera 1 is able toeffectively use a correction range of OIS lens 220 at interchangeablelens 200.

Second Exemplary Embodiment

Another exemplary configuration of the digital camera that implementsthe shake correction will be described below. The configuration of thedigital camera according to the second exemplary embodiment is the sameas that of the first exemplary embodiment except for the OIS processingunit and BIS processing unit.

FIG. 7 is a block diagram illustrating a configuration of OIS processingunit 223 of digital camera 1 according to the second exemplaryembodiment. OIS processing unit 223 according to the second exemplaryembodiment includes ADC/LPF 305, HPF 306, phase compensation unit 307,integrator 308, and PID control unit 311. Functions of these structuralelements are the same as those described in the first exemplaryembodiment. OIS processing unit 223 according to the second exemplaryembodiment further includes position shift unit 312 configured to shifta center position of movement of OIS lens 220 according to aninstruction from lens controller 240. Specifically, position shift unit312 causes the center position of the movement of OIS lens 220 to bereflected in an output, i.e., the shake correction signal, fromintegrator 308. Hereinafter, the signal output from position shift unit312 will be referred to as “OIS control signal.”

FIG. 8 is a block diagram illustrating a configuration of BIS processingunit 183 of digital camera 1 according to the second exemplaryembodiment. BIS processing unit 183 according to the second exemplaryembodiment includes ADC/LPF 405, HPF 406, phase compensation unit 407,integrator 408, and PID control unit 410. Functions of these structuralelements are the same as those described in the first exemplaryembodiment. BIS processing unit 183 according to the second exemplaryembodiment further includes position setting unit 413 and selector 414.Position setting unit 413 outputs a signal for setting a position of CCD110. Selector 414 selects one of the output from PID control unit 410and the output from position setting unit 413 and outputs the selectedone to CCD driving unit 181. Position setting unit 413 and selector 414are controlled by camera controller 140. Hereinafter, the output fromposition setting unit 413 will be referred to as “BIS control signal.”

In the second exemplary embodiment, digital camera 1 uses only the OISfunction in interchangeable lens 200 to perform the shake correction.For that purpose, selector 414 of BIS processing unit 183 is configuredto select the output from position setting unit 413. In a case wherecamera body 100 implements the shake correction function by itself tomeet such circumstances of an interchangeable lens that does not have ashake correction function, selector 414 selects the output from PIDcontrol unit 410.

In a shake correction process according to the second exemplaryembodiment, digital camera 1 centers OIS lens 220 particularly at thebeginning of the exposure period to perform the shake correction duringthe exposure period. That is, digital camera 1 shifts the position ofOIS lens 220 that has not been moved for the shake correction to acenter position of a movable range of OIS lens 220. By centering OISlens 220 as described above, digital camera 1 is able to effectively usethe correction range during the exposure period available for OIS lens220.

FIG. 9 is a flow chart showing steps of the shake correction process indigital camera 1 according to the second exemplary embodiment. Asdescribed above when digital camera 1 is not in the exposure period (ina live view display state), it activates only the OIS function (S11). Inresponse to pushing of release button 130 by the user (YES in S12),camera controller 140 transmits a release signal which indicates thedepression of release button 130 to lens controller 240 via body mount150 and lens mount 250. In response to reception of the release signal,lens controller 240 stores information indicating a current position ofOIS lens 220 in DRAM 241 and controls OIS processing unit 223 to centerthe position of OIS lens 220 (to move to the center position) (S13). Onthat occasion, the OIS control signal for shifting the center positionof the movement of OIS lens 220 is generated by position shift unit 312.Further, lens controller 240 transmits the positional information of OISlens 220 stored in DRAM 241 to camera body 100 via lens mount 250 andbody mount 150 (S14). Incidentally, lens controller 240 may transmit thepositional information of OIS lens 220 by using the ordinarylens-to-camera body communication or by adding the positionalinformation to the low-frequency shake correction signal transmittedfrom interchangeable lens 200.

In response to reception of the positional information of OIS lens 220from interchangeable lens 200, camera controller 140 of camera body 100converts the received positional information (the position of OIS lens220 immediately before the centering) into an amount of movement of CCD110 and calculates a target position for the movement of CCD 110. Cameracontroller 140 controls BIS processing unit 183 to move CCD 110 to thetarget position for the movement (S15). On that occasion, the BIScontrol signal for moving CCD 110 to the target position for themovement is generated by position setting unit 413. During the exposureafter S15, BIS processing unit 183 keeps CCD 110 at the targetedposition (S16).

In response to the end of exposure, camera controller 140 notifies lenscontroller 240 of the end of exposure. Lens controller 240 reads out thepositional information from DRAM 241 and controls OIS processing unit223 to move OIS lens 220 to the position indicated by the positionalinformation (S17). On that occasion, the BIS control signal for movingCCD 110 to the position indicated by the positional information isgenerated by position setting unit 413. Further, BIS processing unit 183returns CCD 110 to a predetermined center position for CCD 110 (S18). Onthat occasion, the BIS control signal for moving CCD 110 to thepredetermined center position is generated by position setting unit 413.

FIG. 10 is a graph showing changes in the shake detection signal (theoutput from integrator 308), the BIS control signal (the output fromposition shift unit 312), and the OIS control signal (the output fromposition setting unit 413) in the above described shake correctionprocess. As shown in FIG. 10, OIS lens 220 is controlled to be shiftedto the center position and to be driven around the center position. Onthe other hand, CCD 110 is shifted and fixed to a position correspondingto the position of OIS lens 220 at which OIS lens 220 has been stayedimmediately before the centering. During the period other than theexposure period, OIS lens 220 is controlled to be driven around anoriginal center position and CCD 110 is also fixed to an original centerposition.

As described above, at the beginning of the exposure period, digitalcamera 1 according to the second exemplary embodiment centers OIS lens220 and shifts CCD 110 by an amount corresponding to the amount ofmovement for centering OIS lens 220. Then, digital camera 1 executes theOIS function with CCD 110 fixed to the position. In response to the endof exposure, digital camera 1 returns OIS lens 220 to the position atwhich OIS lens 220 has been stayed immediately before the centering andalso returns CCD 110 to the predetermined center position.

By centering OIS lens 220 at the beginning of the exposure, digitalcamera 1 is able to effectively use the correction range during theexposure available for OIS lens 220. Further, by moving CCD 110 tooffset the amount of the centering of OIS lens 220, digital camera 1 isable to prevent the centering from causing a deviation of an angle ofview. As a result, digital camera 1 is able to allow the user to capturean image from the same angle of view as that the user has checked beforethe exposure and is also able to effectively use the image blurcorrection.

Also in the second exemplary embodiment, OIS processing unit 223 may beconfigured to generate the high-frequency shake correction signal anddrive OIS lens 220 based on the high-frequency shake correction signal.With that configuration, during the exposure period, digital camera 1only needs to shift CCD 110 to the position corresponding to the amountof the centering of OIS lens 220 and does not need to drive CCD 110based on the low-frequency shake correction signal. Still further,digital camera 1 may be configured to drive CCD 110 during the exposureperiod based on the low-frequency shake correction signal around theposition to which CCD 110 has been shifted correspondingly to the amountof the centering of OIS lens 220. FIG. 11 and FIG. 12 show aconfiguration of OIS processing unit 223 and a configuration of BISprocessing unit 183 for centering OIS lens 220 and also driving OIS lens220 based on the high-frequency shake correction signal and driving CCD110 based on the low-frequency shake correction signal during theexposure period.

As illustrated in FIG. 11, OIS processing unit 223 further includes LPF309 and adder 310 for separating the shake correction signal into thehigh-frequency shake correction signal and the low-frequency shakecorrection signal as well as the configuration illustrated in FIG. 7. Onthe other hand, as illustrated in FIG. 12, BIS processing unit 183includes position shift unit 415 in place of position setting unit 413of the configuration illustrated in FIG. 8 and has selector 414 arrangedat the position different from that of FIG. 8. Operations of thestructural elements illustrated in FIG. 11 and FIG. 12 are basically thesame as those described above. Incidentally, in a case where digitalcamera 1 is to perform the shake correction by separating the shakecorrection signal into the high-frequency shake correction signal andthe low-frequency shake correction signal, selector 414 in BISprocessing unit 183 selects the output from position shift unit 415.

In OIS processing unit 223, the shake correction signal from integrator308 is separated into the high-frequency shake correction signal and thelow-frequency shake correction signal by LPF 309 and adder 310. In thehigh-frequency shake correction signal, the center position of themovement of OIS lens 220 is shifted by position shift unit 312 duringthe exposure period. PID control unit 311 performs the PID control basedon the high-frequency shake correction signal with the center positionshifted and the current positional information of OIS lens 220 receivedfrom position sensor 222 to generate and output a driving signal for OISdriving unit 221.

On the other hand, in BIS processing unit 183, the output from positionshift unit 415 is selected by selector 414. As described above, cameracontroller 140 receives the positional information of OIS lens 220 frominterchangeable lens 200 and calculates an amount of shift for CCD 110based on the received positional information (the position of OIS lens220 at which OIS lens 220 has been stayed immediately before thecentering).

During the period other than the exposure period, position shift unit415 generates a signal for controlling CCD 110 to move to apredetermined home position. On the other hand, during the exposureperiod, position shift unit 415 shifts the center position of CCD 110 bythe calculated amount of shift in the low-frequency shake correctionsignal. As a result, digital camera 1 drives CCD 110 during the exposureperiod to execute the shake correction based on the low-frequency shakecorrection signal around the position to which CCD 110 has been shiftedcorrespondingly to the amount of the centering of OIS lens 220.

In the above described manner, digital camera 1 is able to implement theshake correction during the exposure period by centering OIS lens 220and also by driving OIS lens 220 based on the high-frequency shakecorrection signal and driving CCD 110 based on the low-frequency shakecorrection signal.

Incidentally, in the second exemplary embodiment, digital camera 1activates only the OIS function as the shake correction function.However, digital camera 1 may be configured to activate only the BISfunction as the shake correction function. With that configuration,digital camera 1 only needs to center CCD 110 at the beginning of theexposure period. Further, digital camera 1 only needs to shift OIS lens220 by the amount of movement of OIS lens 220 converted from theposition of CCD 110 at which CCD 110 has been stayed immediately beforethe centering and to fix OIS lens 220 during the exposure period to theposition. By driving CCD 110 around the position on which CCD 110 hasbeen centered as described above during the exposure period, digitalcamera 1 is able to fully use the correction range available for CCD 110(an available driving range) of CCD 110. Further, by shifting OIS lens220 during the exposure period, digital camera 1 is also able to preventa deviation of the angle of view.

In this case, the selection of the function to be activated as the shakecorrection function is preferably based on accuracy of the shakecorrection by the OIS function and by the BIS function and follow-upcharacteristics. Since digital camera 1 according to the secondexemplary embodiment has the OIS function able to perform the shakecorrection with higher accuracy than the BIS function is, digital camera1 selects the OIS function as the shake correction function. With thatconfiguration, digital camera 1 is able to efficiently use the two shakecorrection functions.

3. Other Exemplary Embodiments

The spirit of the above described exemplary embodiments is not limitedto the exemplary embodiments described above. Various exemplaryembodiments may also be considered. Other exemplary embodiments to whichthe spirit of the above described exemplary embodiments can be appliedwill be described below.

The gyro sensor as the shake detection unit is not limited to a sensorconfigured to output an analogue signal and may be a sensor configuredto output a digital signal. In the latter case, gyro sensor 224 and OISprocessing unit 223 transmit data to each other by serial communicationsor the like.

Although the digital camera according to the first exemplary embodimentis configured to have the OIS function which is able to correct theshake with higher accuracy than the BIS function is and to correct thehigh-frequency component of the shake correction signal by using the OISfunction, the present disclosure is not limited to that configuration.In a case where the digital camera has the BIS function which is able tocorrect the shake with higher accuracy than the OIS function is, thedigital camera may correct the high-frequency component of the shakecorrection signal by using the BIS function and correct thelow-frequency component of the shake correction signal by using the OISfunction. In this case, the gyro sensor and the BIS processing unitprovided in the camera body preferably function as the components in themaster.

Although the digital camera according to the second exemplary embodimentis configured to have the OIS function which is able to correct theshake with higher accuracy than the BIS function is and to perform theshake correction during the exposure by using the OIS function, thepresent disclosure is not limited to that configuration. In a case wherethe digital camera has the BIS function which is able to correct theshake with higher accuracy than the OIS function is, the digital cameramay perform the shake correction during the exposure by using the BISfunction. In this case, the digital camera preferably uses the gyrosensor and the BIS processing unit provided in the camera body inperforming processes including the calculation of the amount of shake.

Although the digital cameras according to the first and second exemplaryembodiments are configured to have the OIS function which is able tocorrect the shake with higher accuracy than the BIS function is, thepresent disclosure is not limited to those configurations. The digitalcamera may be configured to cause the interchangeable lens to keepaccuracy information of the OIS function and to cause the camera body tokeep accuracy information of the BIS function so that the digital cameracan select one of the OIS function and the BIS function to give priorityas the shake correction function based on these pieces of accuracyinformation. That is, the digital camera may be configured to cause theaccuracy information kept in the interchangeable lens and the accuracyinformation kept in the camera body to be transmitted to the cameracontroller or the lens controller by the lens-to-camera bodycommunication when the interchangeable lens is mounted to the camerabody so that the digital camera can select one of the OIS function andthe BIS function to give priority as the shake correction function bycomparing these pieces of accuracy information.

Although the digital cameras according to the first and second exemplaryembodiments are configured to use the shake correction accuracy as thecriterion for selecting one of the interchangeable lens and the camerabody as the master, the present disclosure is not limited to thoseconfigurations. The digital camera may be configured to select one ofthe interchangeable lens and the camera body as the master based ondetection accuracy, drift performance, noise performance, shutter shockresistance or mirror shock resistance of the gyro sensor, and so on.Alternatively, the digital camera may be configured to make theselection based on a combination of the shake correction accuracy,performances of the gyro sensor, and so on.

The exemplary embodiments have been described above as examples of thetechnology of the present disclosure. For describing those exemplaryembodiments, the detailed description and the accompanying drawings havebeen disclosed. Consequently, the structural elements described in thedetailed description and shown in the accompanying drawings may includea structural element that is not necessary to solve the problem.Therefore, the unnecessary structural element should not be instantlyrecognized as a necessary structural element merely because it isdescribed in the detailed description and shown in the accompanyingdrawing.

The above described exemplary embodiments are for exemplifying thetechnology of the present disclosure. Therefore, the exemplaryembodiments may be subjected to various changes, substitutions, additionand/or omission or the like without departing from the scope of theclaims and the equivalent of the claims.

The spirit of the present disclosure can be applied to electronicdevices provided with a shake correction function such as an imagingapparatus like a digital camera and a camcorder, a mobile phone, a smartphone, and the like.

What is claimed is:
 1. An imaging apparatus comprising: aninterchangeable lens; and a camera body comprising an imaging deviceconfigured to generate image data by imaging an object image which isformed by the interchangeable lens, wherein the interchangeable lenscomprises: a correction lens configured to correct an image blur; ashake detection unit configured to detect a shake of at least one of thecamera body and the interchangeable lens; a shake correction processingunit configured to calculate an amount of shake correction for thecorrection lens and the imaging device based on an output from the shakedetection unit; and a lens driving unit configured to perform image blurcorrection by moving the correction lens in a plane perpendicular to anoptical axis based on an output from the shake correction processingunit, wherein the camera body further comprises a device driving unitconfigured to perform image blur correction by moving the imaging devicein a plane perpendicular to the optical axis, wherein the lens drivingunit moves the correction lens to a predetermined center position andthe device driving unit shifts the imaging device by an amountcorresponding to an amount of the movement of the correction lens to thecenter position at a beginning of exposure of the imaging device, andwherein the lens driving unit drives the correction lens around thecenter position based on the output from the shake correction processingunit during a period of the exposure.
 2. The imaging apparatus accordingto claim 1, wherein the interchangeable lens further comprises a firstcommunication unit configured to communicate with the camera body, thecamera body further comprises a second communication unit configured tocommunicate with the interchangeable lens, and information indicatingthe amount of the movement of the correction lens is transmitted fromthe interchangeable lens to the camera body via the first communicationunit and the second communication unit.
 3. The imaging apparatusaccording to claim 1, wherein the lens driving unit performs the imageblur correction by moving the correction lens based on a high-frequencycomponent in the output from the shake correction processing unit, andthe device driving unit performs the image blur correction by moving theimaging device based on a low-frequency component in the output from theshake correction processing unit.
 4. An interchangeable lens to bemounted to a camera body including an imaging device configured togenerate image data by imaging an object image which is formed by theinterchangeable lens, the interchangeable lens comprising: a correctionlens configured to correct an image blur; a shake detection unitconfigured to detect a shake of at least one of the camera body and theinterchangeable lens; a shake correction processing unit configured tocalculate an amount of shake correction for the correction lens and theimaging device based on an output from the shake detection unit; a lensdriving unit configured to perform image blur correction by moving thecorrection lens in a plane perpendicular to an optical axis based on anoutput from the shake correction processing unit; and a communicationunit configured to communicate with the camera body, wherein the lensdriving unit moves the correction lens to a predetermined centerposition at a beginning of exposure of the imaging device, and drivesthe correction lens around the center position based on the output fromthe shake correction processing unit during a period of the exposure,and wherein the communication unit transmits to the camera bodyinformation indicating an amount of the movement of the correction lensto the center position at the beginning of the exposure.
 5. A camerabody to which an interchangeable lens is to be mounted, the camera bodycomprising: an imaging device configured to generate image data byimaging an object image which is formed by the interchangeable lens; adevice driving unit configured to perform image blur correction bymoving the imaging device in a plane perpendicular to an optical axis;and a first communication unit configured to communicate with theinterchangeable lens, wherein the interchangeable lens comprises: acorrection lens configured to correct an image blur; a shake detectionunit configured to detect a shake of at least one of the camera body andthe interchangeable lens; a shake correction processing unit configuredto calculate an amount of shake correction for the correction lens andthe imaging device based on an output from the shake detection unit; alens driving unit configured to perform image blur correction by movingthe correction lens in a plane perpendicular to the optical axis basedon an output from the shake correction processing unit; and a secondcommunication unit configured to communicate with the camera body,wherein the lens driving unit moves the correction lens to apredetermined center position at a beginning of exposure of the imagingdevice, and drives the correction lens around the center position basedon the output from the shake correction processing unit during a periodof the exposure, wherein the first communication unit receives from theinterchangeable lens information indicating an amount of the movement ofthe correction lens to the center position, wherein the device drivingunit is configured to shift the imaging device during the period ofexposure of the imaging device by an amount corresponding to the amountof the movement indicated by the received information, and wherein thesecond communication unit transmits to the camera body the informationindicating the amount of the movement of the correction lens to thecenter position at the beginning of the exposure.